One bad thing about google fi is if you forget the google account password & email that you associate with the phone number and don't have a 'backup email' for it, it's near impossible to close the account or similar and have it stop charging your credit card until you do a chargeback. Which also means random people can charge your credit card on a subscription.

Google support cannot do anything on their end to get google to stop charging your credit card, and you have to do a chargeback on your side as a result.